Earlier this year, the "Mediterranean diet" turned 15. Of course, for the people who actually live in the Mediterranean region, that's an absurd notion. They have been eating meals of fish, vegetables, and whole grains drizzled with olive oil, then washing it all down with a glass or two of wine for generations. What actually turned 15 is the Mediterranean Diet Pyramid, an attempt by nutrition experts to promote an alternative to the typical overprocessed, fat- and sugar-laden American diet.
That pyramid—like other recently devised dietary guides built on age-old traditions—represents a way of looking at nutrition that's gathering steam these days. Rather than reducing a diet to its essential foods and then foods to their essential nutrients—vitamins, minerals, and other chemicals—and trying to isolate those that may contribute to good health, researchers are increasingly taking a step back and correlating health with broader eating patterns. "What we're talking about is the background diet," says Linda Van Horn, acting chair of preventive medicine at Northwestern University's Feinberg School of Medicine. "It's not the occasional hot fudge sundae or brownie; rather, it's the day-to-day, meal-to-meal, bite-to-bite: What is it that appears in your mouth?"
The focus is on finding the overall combination of foods that are associated with better health, without necessarily pinpointing individual elements of the diet that are responsible. That may involve studying how people in different areas of the world eat or, here at home, using statistics to study which foods the healthiest among us consume. "You find out who's healthy, then ask what they're eating and how much they exercise," says K. Dun Gifford, founder and president of Oldways Preservation Trust, the Boston-based food issues think tank that developed the Mediterranean Diet Pyramid. (More later on the exercise element, which often gets lost when people try to adopt a healthier diet.)
Oldways, which gets funding from food companies and trade associations, among others, and developed its recommendations in conjunction with the Harvard School of Public Health, has also created food pyramids for a traditional healthful Asian diet, which emphasizes vegetables such as bok choy and chilies, noodles, and beans, as well as a traditional Latin American diet. The group has also cooked up a healthful vegetarian pyramid; plant-based diets, when they include all the essential nutrients, are associated with low rates of chronic diseases and longevity.
A new paradigm. It's important to recognize the flaws in the old-fashioned approach to nutrition science, which is to search for the precise health-promoting vitamin or chemical in a food and then to isolate it. That often results in taking wonder ingredient X out of the food entirely and putting it into a pill or into foods it was never meant to be in (think orange juice spiked with the omega-3 fatty acids naturally found in fish). That kind of ingredient isolation and supplementation was appropriate when many people suffered from diseases caused by a lack of a certain nutrient, like scurvy (vitamin C) or rickets (vitamin D). Those problems could easily be fixed by adding back the missing piece. "But there's a big difference between deficiency diseases and chronic diseases, where it's more likely that there are multiple factors acting in concert," says Marion Nestle, a nutritionist at New York University and author of, most recently, What to Eat. "It's hard, in that situation, to tease out the role of a single nutrient."
Not that people haven't tried. Consider the health claims for various vitamins, minerals, and other nutrients over the years. Vitamins A and C, which are antioxidants, and carotenoids like beta carotene and lycopene were once touted as tools to fight chronic diseases like cancer. It was a logical hypothesis; people who eat a lot of fruits and veggies are healthier than those who don't. Shouldn't the chemicals that are unique to these foods be responsible? As it turns out, no. "The history has been that the first studies [to test individual nutrients] show fabulous benefits, and then as they were repeated with larger populations, better placebos, and better controls, not only were they not helping, but in some cases they may hurt," says Nestle. The poster child is beta carotene, which not only didn't stave off lung cancer but actually appeared to increase rates of the disease among smokers. (A similar outcome was reported earlier this year with vitamin E.) Now we're back to where we started: Fruits and veggies appear to be protective, but we still don't know why.